For background reference is made to U.S. Pat. No. 4,061,890 entitled LOUDSPEAKER WITH SINGLE LAYER RECTANGULAR WIRE VOICE COIL WOUND ON SLIT METAL BOBBIN WITH A NOTCH IN THE ADJACENT POLE PLATE of Thomas A. Froeschle granted Dec. 6, 1977, and U.S. Pat. No. 4,158,756 entitled DYNAMIC LOUDSPEAKER WITH PLASTIC BASKET ENCAPSULATING FRONT POLE PLATE of William J. Keezer granted June 19, 1979. These patents disclose a loudspeaker driver embodied in the commercially available BOSE 901 loudspeaker system and the Delco-GM-Bose music system. These patents disclose a loudspeaker driver having a molded plastic basket made of thermoplastic polyester with glass fill and a front pole plate of low reluctance magnetic material molded into the base of the basket with a keyed central bore. The motor structure is located behind the front pole plate. The edge of the spider that resiliently supports the voice coil is fastened to an annular surface inside the basket. A low resistance single layer anodized aluminum rectangular wire voice coil is wound on a slit anodized aluminum bob-bin. There is a notch in the adjacent pole plate for the return length of the voice coil wire. This loudspeaker driver exhibits excellent electro-acoustical and mechanical characteristics and operates satisfactorily under a wide range of environmental conditions.
It is an important object of this invention to provide an improved loudspeaker driver.